| FXS | Foreign eXchange Subscriber | In English | |
| GCC | Ground Communications Coordinator | In English | |
| GCF | Ground Communications Facility | In English | |
| GCN | Ground Communications Network | In English | → Networks, communication |
| GCS | Ground Communications System | In English | |
| GCS | Guidance Cutoff Signal | In English | |
| GCTS | Ground Communication Tracking System | In English | |
| GEPRAF | Grupo de Esperanto-Parolantaj Radio-Amatoroj en Francio | In Esperanto | → Organizations and associations |
| GET | Groupe des Écoles des Télécommunications | In French | → Organizations and associations → Specialized or (poly)technical colleges |
| GET | Groupe des Écoles de Télécommunications (www.get-telecom.fr) | In French | → Organizations and associations → Specialized or (poly)technical colleges |
| GGSN | Gateway GPRS Support Node | In English | |
| GHM | Groupe Hersant Médias | In French | → Graphic industries, printing, publishing |
| GHZ | Gigahertz | In English | → Physics |
| GITEP | Groupement des Industries de Télécommunications et d'Électronique Professionnelle | In French | → Organizations and associations → Electronics |
| GITEP TICS | Groupement des Industries des Technologies de l'Information et de la Communication | In French | → Organizations and associations → Computer science" |
| GMMAFG | Global Multimedia Mobility Architecture Framework Group | In English | → Organizations and associations |
| GMMCG | Global Multimedia Mobility Co-ordination Group | In English | → Organizations and associations |
| GMSC | Gateway Mobile Service Switching Center | In English | |
| GPON | Gigabit Passive Optical Network | In English | |
| GPR | Ground Penetrating Radar | In English | |
| GPRS | General Packet Radio Service | In English | |
| GPS | Global Positioning System | In English | → Geodesy, cartography → Spaceflight engineering, astronautics |
| GRMC | Groupement de Radiodiffusion Monégasque | In French | |
| GRPS | General Packet Radio Service | In English | |
| GSTAR | Saudi Arabian Communications Satellite | In English | → Spaceflight engineering, astronautics |
| GTE | General Telephone and Electronics | In English | → Electronics |
| GTR | Génie des Télécommunications et des Réseaux | In French | → Networks, communication |
| GTS | GSM (Global System for Mobile Communications) Technical Specification | In English | |
| HALTE | Hologram Authentication Labels Technologies | In English | → Optics |
| HDTV | High-Definition Television | In English | |
| HDTV | High Definition Television | In English | |
| HFRA | High-Frequency Recovery Antenna | In English | |
| HFX | High-Frequency Transceiver | In English | |
| HG | High Gain | In English | |
| HGA | High-Gain Antenna | In English | |
| HGAS | High-Gain Antenna System | In English | |
| HHI | Heinrich-Hertz-Institut (www.hhi.fraunhofer.de) | In German | → Research institutes |
| HLR | Home Location Register | In English | |
| HPA | High-Power Antenna | In English | |
| HRT | Hrvatska Radiotelevizija (www.hrt.hr) | In Croatian | |
| HSCS | High-Speed Communications Subsystem | In English | |
| HSCSD | High Speed Circuit Switched Data | In English | |
| HSDPA | High Speed Downlink Packet Access | In English | |
| I3S | (Laboratoire d')Informatique, Signaux et Systèmes de Sophia Antipolis | In French | → Research institutes → Computer science |
| IACR | International Association for Cryptologic Research (www.iacr.org) | In English | → Associations → Mathematics |
| IAF | Internet Access Facilities | In English | → Internet |
| IAIK | Institut für Angewandte Informationsverarbeitung und Kommunikationstechnologie (www.iaik.tugraz.at) | In German | → Computer science |
| IANIS | Innovative Actions Network for the Information Society | In English | → Computer science |
| IAPM | IEEE (Institute of Electrical and Electronics Engineers) Antennas Propagation Magazine | In English | → Serial publications, periodicals |
| IAS | Interface d'Authentification Serveur | In French | → Networks, communication |
| IAS | Identification, Authentification et Signature | In French | → Computer science |
| IAS | Identifizierung, Authentifizierung, Signierung | In German | |
| IBA | Israel Broadcasting Authority (www.iba.org.il) | In English | |
| IBB | International Broadcasting Bureau | In English | |
| IC | Intercommunications | In English | → Networks, communication |
| IC/ES | Intercommunication/Emergency Station | In English | |
| ICAD | International Conference on Auditory Display | In English | → Congresses → Human-computer interaction |
| ICIE | Institute for Communications and Information Engineering | In English | → Computer science |
| IComM | IEEE (Institute of Electrical and Electronics Engineers) Communications Magazine | In English | → Serial publications, periodicals → Networks, communication |
| ICOS | Integrated Communications Organizing Standard | In English | → Standardization |
| ICS | Intercommunication System | In English | → Networks, communication |
| ICS | Interphone Control Station | In English | |
| ICT | Informatie- en Communicatietechnologie = TIC | Tecnologías de la Información y la Comunicación | In Spanish = IKT | Informations- und Kommunikationstechnologie | In German = TIC | Technologies de l'Information et de la Communication | In French = ICT | Information and Communications Technology | In English = IKT | Informations- og kommunikationsteknologi | In Danish = IKT | Inligtings- en kommunikasietegnologie | In Afrikaans = TMK | Teknologi Maklumat dan Komunikasi | In Malay |
In Dutch | → Computer science |
| ICT | Information and Communications Technology = TIC, IKT, TMK (look above) |
In English | → Computer science |
| IDATE | Institut de l'Audiovisuel et des Télécommunications en Europe | In French | → Cinema, movies |
| IDIOM | Information Diffusion across Interactive Online Media | In English | → 007 → Newspapers, journalism |
| IEDR | Ireland's Domain Registry | In English | → Networks, communication |
| IEEEN | IEEE (Institute of Electrical and Electronics Engineers) Network | In English | → Serial publications, periodicals → Computer science |
| IEREJ | Institution of Electronic Radio Engineers Journal | In English | → Serial publications, periodicals → Electronics |
| IETE | Institution of Electronics Telecommunication Engineers | In English | → Serial publications, periodicals → Electronics |
| IETS | Interim European Telecommunications Standard | In English | → Standardization |
| IF | Intermediate Frequency | In English | |
| IF/FDM | Intermediate Frequency/Frequency Division Multiplexer | In English | |
| IGF | Internet Governance Forum | In English | |
| IGMP | Internet Group Management Protocol | In English | → Networks, communication |
| IIT | Istituto di Informatica e Telematica | In Italian | → Computer science |
| IJACS | International Journal of Adaptive Control and Signal Processing | In English | → Serial publications, periodicals |
| IJIMW | International Journal of Infrared and Millimeter Waves | In English | → Serial publications, periodicals → Electricity, magnetism, electromagnetism |
| IJSAC | IEEE (Institute of Electrical and Electronics Engineers) Journal on Selected Areas in Communications | In English | → Serial publications, periodicals |
| IJSC | International Journal of Satellite Communications | In English | → Serial publications, periodicals → Spaceflight engineering, astronautics |
| IKT | Informations- og kommunikationsteknologi = ICT, TIC, TMK (look above) |
In Danish | → Computer science |
| IKT | Inligtings- en kommunikasietegnologie = ICT, TIC, TMK (look above) |
In Afrikaans | → Computer science |
| IKT | Informations- und Kommunikationstechnologie = ICT, TIC, TMK (look above) |
In German | → Computer science |
| ILCSM | IEEE (Institute of Electrical and Electronics Engineers) LCS Magazine | In English | → Serial publications, periodicals |
| ILEC | Incumbent Local Exchange Carrier | In English | |
| ILERA | Internacia Ligo de Esperantistaj Radioamatoroj | In Esperanto | → Organizations and associations |
| ILTS | IEEE (Institute of Electrical and Electronics Engineers) LTS | In English | → Serial publications, periodicals |
| IMAP | Internet Message Access Protocol | In English | → Networks, communication |
| IMEI | International Mobile Equipment Identity | In English | |
| IMGWL | IEEE (Institute of Electrical and Electronics Engineers) Microwave and Guided Wave Letters | In English | → Serial publications, periodicals |
| IMPS | Instant Messaging and Presence Service | In English | |
| IMS | IP Multimedia Subsystem | In English | → Computer science |
| IMSI | International Mobile Subscriber Identity | In English | |
| IMSO | International Mobile Satellite Organization | In English | → Associations → Spaceflight engineering, astronautics |
| INAP | Intelligent Network Application Part | In English | → Networks, communication |
| INCITS | International Committee for Information Technology Standards | In English | → Standardization → Computer science |
| INFRAWEBS | Intelligent Framework for Generating Open (Adaptable) Development Platforms for Web - Service Enabled Applications | In English | → Software → Internet |
| INPT | Institut National des Postes et Télécommunications | In French | → Specialized or (poly)technical colleges |
| INSAT | India Communications Satellite | In English | → Spaceflight engineering, astronautics |
| INSTAC | Information Technology Research and Standardization Center | In English | → Computer science |
| INTAP | Interoperability Technology Association for Information Processing | In English | → Associations → Computer-based techniques |
| INTELSAT | International Telecommunications Satellite | In English | → Spaceflight engineering, astronautics |
| INTSR | Itogi Nauki i Tekhniki Seriia Radiotekhnika | In Russian | → Serial publications, periodicals |
| IPA | Information-technology Promotion Agency | In English | → Computer science |
| IPA | Internet Privatstiftung Austria | In German | → Foundations → Networks, communication |
| IPCRP | IEE Proceedings: Communications and Radar Processing | In English | → Serial publications, periodicals → Electrical engineering |
| IPCRS | IEE Proceedings: Communications Radar and Signal Processing | In English | → Serial publications, periodicals → Electrical engineering |
| IPER | Innovation dans les Processus de l’Entreprise par la RFID | In English | → Networks, communication |
| IPF | Internet pour la France | In French | → Internet → Organizations and associations |
| IPMAP | IEE Proceedings: Microwaves Antennas and Propagation | In English | → Serial publications, periodicals |
| IPMOA | IEE Proceedings: Microwaves Optics and Antennas | In English | → Serial publications, periodicals → Optics |
| IPRSP | IEE Proceedings: Radar and Signal Processing | In English | → Serial publications, periodicals |
| IPTEA | Internacia Poŝtista kaj Telekomunikista Esperanto-Asocio | In Esperanto | → Associations → Transport and postal services |
| IPTL | IEEE (Institute of Electrical and Electronics Engineers) Photonics Technology Letters | In English | → Serial publications, periodicals → Optics |
| IRANSAT | Iranian government communications satellite | In English | → Spaceflight engineering, astronautics |
| IRCCyN | Institut de Recherche en Communications et Cybernétique de Nantes (www.irccyn.ec-nantes.fr) | In French | → Research institutes → Electronics |
| IRCFE | Infrared Communications Flight Experiment | In English | → Spaceflight engineering, astronautics |
| IrDA | Infrared Data Association | In English | → Associations |
| IRE | INstitute of Radio Engineers | In English | |
| IRT | Institut für Rundfunktechnik (www.irt.de) | In German | → Research institutes |
| ISDB | Integrated Services Digital Broadcasting | In English | |
| ISDN | Integrated Services Digital Network | In English | |
| ISDP | IntelliLight Shared Dual Path | In English | → Networks, communication |
| ISIS | Ingénierie des Systèmes d'Information et de Sécurité | In French | → Computer science |
| ISM | ISDN (Integrated Services Digital Network) Standards Management | In English | → Networks, communication |
| ISP | Internet Service Provider | In English | |
| ISPG | Information Services Procurement Group | In English | |
| ISPL | Information Services Procurement Library | In English | |
| ISPL | IEEE (Institute of Electrical and Electronics Engineers) Signal Processing Letters | In English | → Serial publications, periodicals |
| ISPM | IEEE (Institute of Electrical and Electronics Engineers) Signal Processing Magazine | In English | → Serial publications, periodicals |
| ISSS | Information Society Standardization System | In English | → Standardization → Computer science |
| ISTAG | Information Society Technologies Advisory Group | In English | → Organizations and associations → Networks, communication |
| ISTI | Istituto di Scienza e Tecnologie dell'Informazione | In Italian | → Computer science |
| IT | Informatie Technologie | In Frisian | → Computer science |
| IT | Information Technology = IT | Informationstechnik | In German = IT | Inligtingstegnologie | In Afrikaans = TI | Tecnologia da Informação | In Portuguese = TI | Tecnoloxías da información | In Galician |
In English | → Computer science |
| IT | Informationstechnik = TI (look above) |
In German | → Computer science |
| IT | Inligtingstegnologie = TI (look above) |
In Afrikaans | → Computer science |
| ITA | International Telegraph Alphabet | In English | |
| ITAA | Information Technology Association of America | In English | → Associations → Computer science |
| ITAP | IEEE (Institute of Electrical and Electronics Engineers) Transactions on Antennas and Propagation | In English | → Serial publications, periodicals |
| ITASS | IEEE (Institute of Electrical and Electronics Engineers) Transactions on Acoustics, Speech and Signal Processing | In English | → Serial publications, periodicals → Acoustics → Language, linguistics, literature |
| ITB | IEEE (Institute of Electrical and Electronics Engineers) Transactions on Broadcasting | In English | → Serial publications, periodicals |
| ITCom | IEEE (Institute of Electrical and Electronics Engineers) Transactions on Communications | In English | → Serial publications, periodicals |
| ITEA | Information Technology for European Advancement | In English | → Computer science |
| ITIL | IT Infrastructure Library | In English | → Libraries → Computer science |
| ITS | Institut de Traitement des Signaux | In French | → Computer-based techniques |
| ITS | Institute for Telecommunications Sciences | In English | |
| ITSC | Interregional Telecommunications Standards Committee | In English | → Organizations and associations → Networks, communication |
| ITSP | IEEE (Institute of Electrical and Electronics Engineers) Transactions on Signal Processing | In English | → Serial publications, periodicals |
| ITSTC | Information Technology Steering Committee | In English | → Organizations and associations → Computer science |
| ITU | International Telecommunication Union = IUT | Internacia Unio pri Telekomunikado | In Esperanto = UIT | Union Internationale des Télécommunications | In French |
In English | → Organizations and associations |
| ITU-T | International Telecommunications Union - Telecommunications Standardization Sector | In English | → Standardization |
| ITUFF | IEEE (Institute of Electrical and Electronics Engineers) Transactions on Ultrasonics, Ferroelectrics and Frequency Control | In English | → Serial publications, periodicals → Acoustics → Electricity, magnetism, electromagnetism |
| İTV | İctimai Televiziya və Radio Yayımları Şirkəti (www.itv.az) | In Azerbaijani | |
| IUT | Internacia Unio pri Telekomunikado = ITU, UIT (look above) |
In Esperanto | → Organizations and associations |
| IVR | Interactive Voice Recognition | In English | → Computer-based techniques |
| JHSN | Journal of High Speed Networks | In English | → Serial publications, periodicals → Networks, communication |
| JIETE | Journal of the Institution of Electronics and Telecommunication Engineers | In English | → Serial publications, periodicals → Electronics |
| JOC | Journal of Optical Communications | In English | → Serial publications, periodicals → Optics |
| JRN | Japan News Network | In English | |
| JRN | Japan Radio Network | In English | |
| JRTV | Jordan Radio and Television Corporation (www.jrtv.gov.jo) | In English | |
| LAN | Local Area Network | In English | → Networks, communication |
| LAP | London Action Plan | In English | |
| LEAT | Laboratoire d'Électronique, Antennes et Télécommunications | In French | → Research institutes → Electronics |
| LFRR | Low-Frequency Radio Range | In English | |
| LGA | Low-Gain Antenna | In English | |
| LJB | Libya Jamahiriya Broadcasting (http://en.ljbc.net) | In English | |
| LPA | Log Periodic Antenna | In English | |
| LPIC | Ligue de Protection des Internautes Câblés | In French | → Internet → Organizations and associations → Consumerism |
| LR | Latvijas Radio (www.radio.org.lv) | In Latvian | |
| LRT | Lietuvos nacionalinis radijas ir televizija (www.lrt.lt) | In Lithuanian | |
| LTE | Long Term Evolution | In English | |
| LTSI | Laboratoire Traitement du Signal et Instrumentation | In French | → Research institutes |
| LUSSI | Logique des Usages, Sciences Sociales et sciences de l'Information | In French | → Sociology → Computer science |
| MAC | Media Access Control | In English | → Networks, communication |
| MAC | Media Access Controller | In English | |
| MAPEC | Multimedia Applications in Education Conference | In English | → Education |
| MARSOUIN | Môle Armoricain de Recherche sur la SOciété de l'Information et les Usages d 'Internet | In French | → Networks, communication |
| MASCOTTE | Méthodes Algorithmiques, Simulation, Combinatoire et OpTimisation pour les TElécommunications | In French | → Computer science |
| MBS | Malagasy Broadcasting System | In English | |
| MCR | Monte-Carlo Radiodiffusion | In French | |
| MCTI | Ministerul Comunicaţiilor şi Tehnologiei Informaţiei | In Romanian | → Computer science → Central administration |
| MDR | Mitteldeutsche Rundfunk (www.mdr.de) | In German | |
| MDR | Mitteldeutscher Rundfunk | In German | |
| MEECN | Minimum Essential Emergency Communication Network | In English | → Networks, communication |
| MESH | Multimedia Semantic Syndication for Enhanced News Services (www.mesh-ip.eu) | In English | → Computer-based techniques |
| MFSK | Multifrequency Shift Keying | In English | |
| MFSP | Macrofunction Signal Processor | In English | → Electronics |
| MHF | Medium High Frequency | In English | |
| MIAU | Multiple Internet Agents for User-adaptive Decision | In English | → Networks, communication |
| MICNS | Modular Integrated Communication and Navigation System | In English | |
| MIMOSA | Migration et Mobilité - Sémantique et Applications | In French | → Computer-based techniques → Semiotics |
| MITOC | Missile Intercom Technical Operational Communication | In English | → Military engineering |
| MMG | Multimedia Management Group | In English | → Management |
| MMS | Multimedia Messaging Service | In English | |
| MMSC | Multimedia Messaging Service Center | In English | |
| MOPS | Military Operation Phone System | In English | → Military engineering |
| MPT | Ministry of Posts and Telecommunications | In English | → Organizations and associations → Transport and postal services |
| MR | Magyar Rádió | In Hungarian |